1. Field of the Invention
The invention relates to the field of hand-held input devices for computers and more particularly to a hand-held assembly which includes both a bar code wand and light pen.
2. Description of the Prior Art
Cathode ray tubes (CRT) are extensively used in displays at computer terminals wherein information is processed. CRT displays at computer terminals both provide the function of displaying information and for inputting information. Information may be input by means of a light pen which is used to select displayed entries. Thus in combination with a light pen, a CRT display becomes both an input and output device.
Similarly, a bar code scanning wand has been used in many applications as an input device for information processing systems, typically point of sale terminals or inventory systems. The use of bar code scanning permits fast, accurate and keyless data entry. Although it is known in the art to separately provide light pens and bar coded wands as input devices in connection with computers and CRT displays, no practical device has been devised whereby both input elements may be included within a single hand-held assembly.
Attempts have been made in the prior art to use a single sensor to function both as light pen and a bar code reader. For example, MONTEATH et al., "Apparatus Using a Light Sensing System Sensing Time Modulated Information from a Light-Emitting Device", U.S. Pat. No. 4,329,684 (1982), uses time modulation and demodulation of information obtained from light emitters and detectors. By detecting the type of modulation provided to the CRT display on one hand, or received from a bar code reflection on the other hand, the input information is decoded depending upon whether the sensor is being used as a light pen or bar code wand. This requires complex circuitry to modulate the CRT display as well as to appropriately decode the modulated signal to determine whether it is detecting a light pen or bar code input. The nature and complexity of the circuitry increases the cost of such an input device and provides a substantial impediment to packaging the necessary circuitry within a single hand-held assembly.
Others in the prior art have incorporated two input devices within a single hand-held assembly, such as shown by TAKAHASHI et al., "Input Pen Assembly", U.S. Pat. No. 4,263,592 (1981), wherein a conventional light pen and a conductive stylus have been combined within a single handheld wand for use with a CRT display on one hand and a digitizing tablet on the other. However, in TAKAHASHI what was combined was an input device having an optical input and a second input device having an electrical or capacitive input. No attempt was made in TAKAHASHI to include two separate optical input devices within a single hand-held assembly.
Therefore, what is needed is a packaging or assembly which can be economically fabricated and included within a single hand-held device for inputting two separate optical signals, such as CRT light pen inputs and bar code inputs without complex circuit designs or modifications.